ark1668ed-bsp/linux/Documentation/devicetree/bindings/input/adc-keys.yaml

# SPDX-License-Identifier: GPL-2.0
%YAML 1.2
---
$id: http://devicetree.org/schemas/input/adc-keys.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#

title: ADC attached resistor ladder buttons

maintainers:
  - Alexandre Belloni <alexandre.belloni@bootlin.com>

allOf:
  - $ref: input.yaml#

properties:
  compatible:
    const: adc-keys

  io-channels:
    maxItems: 1

  io-channel-names:
    const: buttons

  keyup-threshold-microvolt:
    description:
      Voltage above or equal to which all the keys are considered up.

  poll-interval: true
  autorepeat: true

patternProperties:
  '^button-':
    type: object
    $ref: input.yaml#
    additionalProperties: false
    description:
      Each button (key) is represented as a sub-node.

    properties:
      label: true

      linux,code: true

      press-threshold-microvolt:
        description:
          Voltage above or equal to which this key is considered pressed. No
          two values of press-threshold-microvolt may be the same. All values
          of press-threshold-microvolt must be less than
          keyup-threshold-microvolt.

    required:
      - linux,code
      - press-threshold-microvolt

required:
  - compatible
  - io-channels
  - io-channel-names
  - keyup-threshold-microvolt

additionalProperties: false

examples:
  - |
    #include <dt-bindings/input/input.h>
    // +--------------------------------+------------------------+
    // | 2.000.000 <= value             | no key pressed         |
    // +--------------------------------+------------------------+
    // | 1.500.000 <= value < 2.000.000 | KEY_VOLUMEUP pressed   |
    // +--------------------------------+------------------------+
    // | 1.000.000 <= value < 1.500.000 | KEY_VOLUMEDOWN pressed |
    // +--------------------------------+------------------------+
    // |   500.000 <= value < 1.000.000 | KEY_ENTER pressed      |
    // +--------------------------------+------------------------+
    // |              value <   500.000 | no key pressed         |
    // +--------------------------------+------------------------+

    adc-keys {
        compatible = "adc-keys";
        io-channels = <&lradc 0>;
        io-channel-names = "buttons";
        keyup-threshold-microvolt = <2000000>;

        button-up {
            label = "Volume Up";
            linux,code = <KEY_VOLUMEUP>;
            press-threshold-microvolt = <1500000>;
        };

        button-down {
            label = "Volume Down";
            linux,code = <KEY_VOLUMEDOWN>;
            press-threshold-microvolt = <1000000>;
        };

        button-enter {
            label = "Enter";
            linux,code = <KEY_ENTER>;
            press-threshold-microvolt = <500000>;
        };
    };
...